1. Field of the Invention
The invention generally relates to MART-1 T cell receptors and their use, for example in the prevention and treatment of melanoma in patients.
2. Description of the Related Art
Locally advanced and metastatic melanoma is well-known to be resistant to standard forms of therapy. Two agents are currently approved for the treatment of stage IV melanoma: (1) the chemotherapy drug DTIC (or Dacarbazine), and (2) interleukin-2 (IL-2) administered in high doses (Tsao, H., et al. 2004. N Engl J Med 351:998-1012; Cochran, A., et al. 2002. Cancer Treatment, Fifth Edition, Charles M. Haskell, ed., W.B. Saunders: 179-198). Both agents incur response rates below 15%, and neither form of therapy has been shown to increase survival in a randomized trial. The addition of more chemotherapy or combinations of chemotherapy with IL-2 (“biochemotherapy” regimens) has failed to improve survival in over 10 randomized clinical trials (Tsao, H. et al. 2004. supra; Eigentler, T. K., et al. 2003. Lancet Oncol 4:748-759).
An important step in the treatment of cancer with immunotherapy has been the identification of tumor antigens capable of stimulating T cell responses. Cytotoxic T cells (“CTLs,” “CD8 T cells”) have been shown to be the major effector cells that mediate tumor rejection. Active immunotherapy with several forms of cancer vaccines has shown that antigen-specific T cells can be activated and lead to anti-tumor responses (Ribas, A., et al. 2003. Trends Immunol 24:58-61).
Adoptive therapy is one approach that can overcome the immunotherapy ceiling of approximately 10-15% objective responses for clinical antitumor activity (Rosenberg, S. A., et al. 2004. Nat Med 10:909-915). It is a form of passive immunotherapy in which a host is directly provided with effectors to react against cancer, such as, for example, by direct presentation of in vitro expanded or modified anti-tumor T cells to the host. Adoptive transfer procedures of large numbers of clonally-expanded antigen-specific T cells into patients with melanoma have been studied. In these studies, patients received a conditioning regimen to deplete endogenous lymphocytes (non-myeolablative but lymphodepleting), together with high doses of interleukin-2 (IL-2). The adoptive transfer of large numbers of antigen-specific CD8+ T cells, generally obtained from tumor infiltrating lymphocytes (TIL), leads to the highest percentage of tumor regressions reported in patients with melanoma. In clinical trials at the NCI Surgery Branch, 50% of patients with metastatic melanoma had objective responses (Dudley, M. E., et al. 2002. Science 298:850-854; Dudley, M. E., et al. 2005. J Clin Oncol, 23:2346-2357). However, the procedure is difficult to implement outside of pilot studies due to its requirement for extensive ex vivo manipulations.
The use of genetic engineering of T cells with T-cell receptors (TCRs) as described herein can make adoptive therapy more broadly applicable, and the insertion of reporter genes in such an approach can further permit the study of their immunobiology and tumor trafficking in vivo. In addition, this approach allows for the generation of large numbers of T cells with specificity for melanoma tumor antigens with a relatively short duration (less than one week) of ex vivo cell manipulation.
The TCR is a complex surface protein complex composed of eight different subunits organized in dimers: the TCR α and β chains, a CD3 ζ:CD3 ζ homodimer, and CD3ε:CD3γ and CD3ε:CD3δ heterodimers. (See FIG. 1.) The TCR chains have distal variable regions (Vα and Vβ) that interact with the MHC/antigen determinant as well as proximal constant regions (Cα and Cβ) (Delves, P. J. and Roitt, I. M. 2000. N Engl J Med 343:108-117). The distal V regions have Ig-like folds, with 3 loops or complimentary determinant regions (CDR) from each chain creating the binding face that interacts with antigen. The CD3 complex is involved in stable TCR expression on the cell surface and signal transduction upon antigen encounter, resulting in a signaling cascade that culminates in T cell differentiation, proliferation and acquisition of effector functions (Pitcher, L. A. and van Oers, N. S. 2003. Trends Immunol 24:554-560). The CD4 and CD8 co-receptors increase the affinity of the TCR/MHC-antigen, which results in enhanced TCR signaling but does not alter the specificity of the TCR-antigen interaction (Gao, G. F. and Jakobsen, B. K. 2000. Immunol Today 21:630-636; Arcaro, A., et al. 2000. J Immunol 165:2068-2076).